Swirl ring and contact element for a plasma arc torch cartridge

ABSTRACT

A swirl ring for a plasma arc torch includes a body configured to at least partially surround and slidingly engage an electrode of the plasma arc torch. The body includes a first end and a second end opposite the first end, the first and second ends defining a longitudinal axis, and at least one protuberance extending from the second end in a direction of the longitudinal axis. The at least one protuberance is configured to engage a switch of the plasma arc torch for sensing a presence of a swirl ring in the plasma arc torch.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/456,813, which was filed on Feb. 9, 2017 and entitled“Moving Crown for Cartridge,” the entire contents of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates generally to the field of plasma arc cuttingsystems and processes. More specifically, the invention relates toimproved consumable components (e.g., swirl rings including contactelements) for operating a plasma arc torch.

BACKGROUND

Plasma arc torches are widely used in the cutting and marking ofmaterials. A plasma arc torch generally includes an electrode and anozzle having a central exit orifice mounted within a torch body,electrical connections, passages for cooling, and passages for arccontrol fluids (e.g., plasma gas). The torch produces a plasma arc,i.e., a constricted ionized jet of a gas with high temperature and highmomentum. Gases used in the torch can be non-reactive (e.g., argon ornitrogen) or reactive (e.g., oxygen or air). During operation, a pilotarc is first generated between the electrode (part of the cathode) andthe nozzle (part of the anode). Generation of the pilot arc can be bymeans of a high frequency, high voltage signal coupled to a DC powersupply and the torch or by means of any of a variety of startingmethods. Plasma arc torches can utilize cartridges including one or moreconsumable components (e.g., a nozzle, electrode, and/or a swirl ring)for ease of installation and operation.

FIGS. 1 and 2 show a cartridge for a prior art plasma arc torch 100having a nozzle 104, a shield 108, an electrode 112, a retaining cap116, a swirl ring 120, and a fixed “crown” or contact element 124disposed about the swirl ring 120. This contact element 124 does notmove relative to the swirl ring 120, e.g., is fixed in an axialdirection relative to the swirl ring 120. The contact element 124 passesa cutting current from a plunger 132 of the plasma arc torch 100 to theelectrode 112. Because plasma cutting requires a high cutting current, asolid electrical connection must be maintained between the plasma arctorch 100 and the electrode 112 to ensure proper operation and to limitor eliminate arcing, which can damage equipment and shorten componentlife.

This “fixed crown” design has a failure mode when the contact element124 is not in full contact with the plunger 132 (e.g., because thecartridge is not fully tightened within the plasma arc torch 100). Inthis failure mode, a gap 228 can be created between the contact element124 and the plunger 132, as shown in FIG. 2. This gap 228 results in apoor electrical connection, and can cause poor performance and componentfailure. In addition, the poor connection can lead to arcing between thecathode (e.g., the plunger 132) and the contact element 124, which candestroy the entire torch instead of just one or more consumablecomponents. What is needed is a consumable cartridge that avoids thisfailure mode and ensures proper and complete contact between the plunger132 and the contact element 124, even if the cartridge is not fullyscrewed on or is otherwise loose.

SUMMARY OF THE INVENTION

The present invention relates to improved consumables (e.g., plasma arctorch cartridges and swirl rings including contact elements) for plasmaarc torches and associated methods of operation. Specifically, thedesign shown and described above in FIGS. 1-2 is modified such that the“fixed crown” above is replaced by a “floating” contact element, whichis a separate piece within the cartridge that is allowed to translate apredetermined distance (e.g., an axial length) within the torch duringinstallation and/or operation in the torch. The contact element can besnap fitted or dropped within a swirl ring or cartridge and confined toa certain region within which there is enough space (or “play”) for thecontact element to slide freely. In such a configuration, proper andcomplete contact with the torch cathode can be maintained even if thecartridge is not fully screwed onto the torch (with the torch cathodebiasing the contact element axially forward). This configurationprotects the torch and ensures that proper electrical contact ismaintained within the torch.

For example, one embodiment includes a “snap fit” design that allows thecontact element to travel in an axial direction at the fault regionduring installation in the torch. Thus, instead of being rigidly fixedto the swirl ring, the contact element is located within a track or setof tracks within the swirl ring and is biased by a spring that pushesthe contact element toward the torch if there is a gap (e.g., because ofan untightened thread). During proper assembly the cathode will push thecontact element forward slightly toward the electrode but still maintaina gap for piloting. The gap and the spring being compressed duringcutting and arc ignition are a result of gas force in the swirl ring andplenum. This freedom of movement of the contact element ensures propermating with the cathode through several stages of cartridge turning andinstallation.

In one aspect, the invention features a consumable cartridge for aplasma arc torch. The consumable cartridge includes a cartridge framehaving a first end and a second end opposite the first end. The firstand second ends defines a longitudinal axis. The second end includes aplurality of discrete retaining features. The consumable cartridge alsoincludes an electrically conductive contact element secured to thecartridge frame by the plurality of discrete retaining features and istranslatable up to a predetermined distance within the cartridge framealong the longitudinal axis at the second end. The contact element has acore, a proximal surface, and a distal surface. The proximal surface isshaped to contact a torch plunger of the plasma arc torch uponinstallation into the plasma arc torch. The distal surface is shaped tocontact an electrode of the plasma arc torch during an operation of theplasma arc torch.

In some embodiments, at least one discrete retaining feature in theplurality of discrete retaining features is configured to engage aswitch for sensing a presence of a cartridge frame, cartridge orretaining cap secured to a torch body of the plasma arc torch. In someembodiments, at least one discrete retaining feature in the plurality ofdiscrete retaining features includes a guide track for interfacing withthe contact element. In some embodiments, the contact element includesat least one guide channel for interfacing with the at least onediscrete retaining feature in the plurality of discrete retainingfeatures. In some embodiments, the plurality of discrete retainingfeatures includes one or more axial stops. In some embodiments, thecartridge frame forms a swirl ring or swirl feature of the plasma arctorch, the first end of the cartridge frame including a set of passagesfluidly connecting an internal surface of the cartridge frame and anexternal surface of the cartridge frame.

In some embodiments, the contact element includes a snap fit feature forcoupling to the cartridge frame. In some embodiments, an electrode isdisposed within the cartridge frame, the electrode interacting with(e.g., including) a spring configured to bias the contact element towarda cathode of the plasma arc torch. In some embodiments, the contactelement is configured to slide along the longitudinal axis duringinstallation in the plasma arc torch upon contact with the torchplunger. In some embodiments, the plurality of discrete retainingfeatures is shaped to matingly engage the contact element and to definea translation path of the contact element within the cartridge frame. Insome embodiments, the plurality of discrete retaining features and thecontact element define a set of vent passages. In some embodiments, thetranslation path has two or more radial interface surfaces between thecontact element and the cartridge frame.

In some embodiments, the contact element includes scalloped edges. Insome embodiments, the contact element includes a cap feature integrallyformed with the core. In some embodiments, the cartridge frame is formedof a thermoplastic. In some embodiments, the cartridge frame is molded.In some embodiments, the contact element is physically separate from anelectrode within the consumable cartridge. In some embodiments, thecontact element is removed from direct physical contact with theelectrode when the plasma arc torch is not in operation. In someembodiments, a thickness between the proximal surface and the distalsurface is at least double a thickness at a perimeter of the core.

In another aspect, the invention features a swirl ring for a plasma arctorch. The swirl ring includes a body shaped to matingly engage anelectrode of the plasma arc torch. The body includes a first end and asecond end. The first and second ends define a longitudinal axis. Thebody also includes a set of protuberances extending from the second endin a direction of the longitudinal axis. At least one protuberanceincludes an interior guide track. The swirl ring also includes anelectrically conductive contact element confined by the set ofprotuberances. The contact element includes at least one guide channelcomplementary to the at least one guide track. An alignment of thecontact element with the swirl ring is facilitated by an interaction ofthe at least one guide channel with the at least one guide track.

In some embodiments, the at least one protuberance defines a region thatthe contact element can occupy during a normal operation of the plasmaarc torch. In some embodiments, the first end includes a set of passagesfluildly connecting an internal surface of the swirl ring and anexternal surface of the swirl ring. In some embodiments, the contactelement includes a snap fit feature for coupling to the body of theswirl ring. In some embodiments, the electrode interacts with orincludes a spring configured to bias the contact element toward acathode of the plasma arc torch. In some embodiments, the contactelement is configured to slide along the longitudinal axis duringinstallation in the plasma arc torch upon contact with a plunger of theplasma arc torch. In some embodiments, one or more protuberances has alinear height of between approximately 5 and 7 millimeters. In someembodiments, one or more protuberances has a linear width of betweenapproximately 1 and 3 millimeters. In some embodiments, one or moreprotuberances has a linear length of between approximately 6 and 8millimeters.

In some embodiments, the set of protuberances defines a translation pathfor the contact element. In some embodiments, the swirl ring and thecontact element define a set of vent passages. In some embodiments, thetranslation path has two or more radial interface surfaces between thecontact element and the swirl ring. In some embodiments, the contactelement includes scalloped edges. In some embodiments, the contactelement has a substantially uniform cross-sectional thickness. In someembodiments, the swirl ring is formed of a thermoplastic. In someembodiments, the swirl ring is molded. In some embodiments, the contactelement is removed from direct physical contact with the electrode whenthe plasma arc torch is not in operation.

In another aspect, the invention features a swirl ring for a plasma arctorch. The swirl ring includes a body configured to at least partiallysurround and slidingly engage an electrode of the plasma arc torch. Thebody includes a first end and a second end opposite the first end. Thefirst and second ends define a longitudinal axis. The body also includesa set of protuberances extending from the second end in a direction ofthe longitudinal axis. At least one of protuberances is configured toengage a switch for sensing a presence of a swirl ring or a retainingcap of the plasma arc torch. In some embodiments, a set of molded swirlholes is integrally formed within the body of the swirl ring. In someembodiments, the swirl ring includes a crimped on, unitary nozzle. Insome embodiments, the swirl ring includes an electrically conductivecontact element confined within the set of protuberances, wherein theset of protuberances includes a set of guide tracks and the contactelement includes a set of guide channels complementary to the set ofguide tracks. In some embodiments, the set of protuberances includes aretaining feature to confine the contact element.

In another aspect, the invention features a consumable cartridge for aplasma arc torch. The consumable cartridge includes a cartridge frameand an electrically conductive contact element confined by the cartridgeframe. The consumable cartridge further includes means for locking thecontact element into the plasma arc torch during an operation of theplasma arc torch. In another aspect, the invention features a consumablecartridge for a plasma arc torch. The consumable cartridge includes acartridge frame. The consumable cartridge (e.g., the frame) furtherincludes means for engaging a consumable sense feature of the plasma arctorch during the operation of the plasma arc torch.

In another aspect, the invention features a method of operation of aplasma arc torch. The method includes installing a consumable cartridgein the plasma arc torch. The consumable cartridge has a cartridge framewith a first end and a second end that define a longitudinal axis. Theconsumable cartridge includes an electrically conductive contact elementconfined by the cartridge frame. The method also includes translatingthe contact element in a first direction along the longitudinal axistoward the first end once contact is made with a torch plunger of theplasma arc torch. The method also includes translating an electrode ofthe plasma arc torch in a second direction opposite the first directionalong the longitudinal axis. The electrode contacts the contact elementduring a plasma (e.g., cutting or gouging) operation of the plasma arctorch. The contact element is separated from the electrode when theplasma arc torch is not performing the plasma operation.

In another aspect, the invention features a method of assembling aplasma arc torch cartridge. The method includes providing a swirl ringhaving body shaped to matingly engage an electrode of a plasma arctorch. The body includes a first end and a second end that define alongitudinal axis. The body also includes a set of protuberancesextending from the second end along a direction of the longitudinalaxis. The set of protuberances includes a set of guide tracks. Themethod also includes providing an electrically conductive contactelement having a set of guide channels complementary to the set of guidetracks of the swirl ring. The method also includes installing thecontact element in the swirl ring, the guide channels of the contactelement matingly engaging the set of guide tracks of the swirl ring.During installation of the contact element into the swirl ring, thecontact element translates a fixed distance along the longitudinal axiswithin the swirl ring until the nozzle is attached to the first end ofthe swirl ring. After installation, the contact element is held securelywithin the plasma arc torch cartridge (e.g., confined within a region,but free to move in an axial direction within the region). In someembodiments, after installation the contact element is able to translatea fixed distance within the plasma arc torch cartridge along thelongitudinal axis. In some embodiments, the translation of the contactelement in a direction of the second end is limited by at least oneretaining feature disposed on an interior surface of at least one of theprotuberances.

In another aspect, the invention features a consumable cartridge for aplasma arc torch. The consumable cartridge includes a body configured toat least partially surround and slidingly engage an electrode of theplasma arc torch. The body includes a distal first end and a proximalsecond end opposite the first end. The first and second ends defining alongitudinal axis. The consumable cartridge also includes anintermediate component configured to be positioned between the body anda safety switch of the plasma arc torch, the intermediate componentincluding at least one discrete protuberance affixed to a proximal endof the intermediate component, the discrete protuberance extending fromthe proximal end of the intermediate component in a direction of thelongitudinal axis. The at least one discrete protuberance is configuredto enable an operation of the plasma arc torch by sensing a presence ofa consumable (e.g., swirl ring or retaining cap) of the plasma arc torchby the safety switch. In another aspect, the invention features a methodof enabling an operation of a plasma arc cutting torch. The methodincludes providing a protuberance on a body of a torch cartridge. Themethod also includes installing the torch cartridge in a plasma arctorch, the protuberance activating a safety switch for sensing apresence of a consumable (e.g., swirl ring or retaining cap) of theplasma arc torch.

In some embodiments, the cartridge includes a spring electrode having a“floating crown” that is located dynamically within the swirl ring ofthe cartridge. In some embodiments, when not in operation, the floatingcrown is not in direct physical contact with the electrode (e.g., iscontacting only the spring connecting the two). In some embodiments, theswirl ring and the floating crown include complementary tracks orguides. In some embodiments, the floating crown has a non-circular shapewith a number of tabs and/or slots that would be expensive and/ordifficult to machine. In some embodiments, an additional set ofalignment surfaces influences electrical contacts within the torch (incertain previous embodiments, the electrode, the contact element, andthe plunger provided such surfaces, whereas here the swirl ring alsoprovides such surfaces). In some embodiments, as installation occurs,the crown translates axially forward once contact is made with the torchplunger, and then when firing the electrode translates back into thefloating crown to fire. In some embodiments, one or more configurationsdescribed herein result in improved consumable alignment. In someembodiments, one or more configurations described herein provide morereliable contact or connection between the plunger and the electrode,even during incomplete installation, which enables faster consumablechanges and reduction in cost.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing discussion will be understood more readily from thefollowing detailed description of the invention when taken inconjunction with the accompanying drawings.

FIG. 1 is a cross-sectional view of a prior art plasma arc torch with aproperly installed “fixed crown” cartridge.

FIG. 2 is a cross-sectional view of a prior art plasma arc torch with animproperly installed “fixed crown” cartridge.

FIG. 3 is a cross-sectional view of a plasma arc torch with a cartridgeincluding a “floating crown” or contact element installed therein,according to an illustrative embodiment of the invention.

FIG. 4A is a cross-sectional view of a swirl ring having a “floatingcrown” or contact element installed therein, according to anillustrative embodiment of the invention.

FIG. 4B is a side view of the swirl ring of FIG. 4A rotated 90 degreesabout a longitudinal axis of the swirl ring, according to anillustrative embodiment of the invention.

FIG. 5A is a side view of a plasma arc torch cartridge having anelectrode and a contact element installed therein, according to anillustrative embodiment of the invention.

FIG. 5B is a top view of the plasma arc torch cartridge of FIG. 5A,according to an illustrative embodiment of the invention.

FIG. 5C is a sectional view of the plasma arc torch cartridge of FIG.5A, according to an illustrative embodiment of the invention.

FIG. 5D is an exploded view of the plasma arc torch cartridge of FIG.5A, according to an illustrative embodiment of the invention.

FIG. 6A is a perspective view of the contact element for a plasma arctorch cartridge shown in FIGS. 5A-5D, according to an illustrativeembodiment of the invention.

FIG. 6B is a top view of a contact element for a plasma arc torchcartridge having scalloped edges, according to an illustrativeembodiment of the invention.

FIG. 7 is a flow diagram illustrating a method of operation of a plasmaarc torch, according to an illustrative embodiment of the invention.

FIG. 8 is a flow diagram illustrating a method of assembling a plasmaarc torch cartridge, according to an illustrative embodiment of theinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 3 is a cross-sectional view of a plasma arc torch 300 with acartridge 304 including a “floating crown” or electrically conductivecontact element 308 installed therein, according to an illustrativeembodiment of the invention. The plasma arc torch 300 has a nozzle 312,a shield 316, an electrode 320, a retaining cap 324, and a swirl ring328. The contact element 308 installed in the plasma arc torch 300includes a spring 332 of the electrode 320 configured to bias thecontact element 308 axially backward toward the plunger (cathode) 332.During proper assembly, the cathode 332 will push the contact element308 slightly forward toward the electrode 320 but still maintain a gapbetween the electrode 320 and the contact element 308 for piloting andarc generation during a beginning of operation. During cutting and/orarc ignition, this gap and the spring will be fully compressed as aresult of gas forces within the swirl ring 328 (and/or plenum). Incontrast to the prior art embodiment shown in FIGS. 1 and 2, thisfreedom of movement of the contact element 308 ensures proper matingwith the cathode 332 through several stages of cartridge turning andinstallation.

FIG. 4A is a cross-sectional view of the swirl ring 328 (e.g., aconsumable cartridge for a plasma arc torch) having a “floating crown”or electrically conductive contact element 308 installed therein,according to an illustrative embodiment of the invention, and FIG. 4B isa side view of the swirl ring of FIG. 4A rotated 90 degrees about alongitudinal axis 404 of the swirl ring 328. The swirl ring 328 has abody 404 (e.g., a cartridge frame) having a first end 408 and a secondend 412 opposite the first end 408, the first and second ends defining alongitudinal axis 416. The second end 412 includes a plurality ofdiscrete retaining features 420A, 420B. The discrete retaining features420A, 420B can be protuberances that take the shape of projections,distensions or longitudinal extensions at the second end 412. In thisembodiment, there are two retaining features 420A, 420B that arediametrically opposed, but in other embodiments there are another numberof discrete retaining features, including three, four, or a differentnumber.

The contact element 308 is secured to the body 404 by the plurality ofdiscrete retaining features 420A, 420B. The contact element 308 has acore 428, a proximal surface 432, and a distal surface 436. The proximalsurface 432 is shaped to contact a torch plunger (e.g., the cathode 332shown and described in FIG. 3) of the plasma arc torch upon installationinto the plasma arc torch. The distal surface 436 is shaped to contactan electrode (e.g., the electrode 320 shown and described in FIG. 3) ofthe plasma arc torch during an operation of the plasma arc torch. Thecontact element 308 is physically separate from the electrode 320 and isremoved from direct physical contact with the electrode 320 when theplasma arc torch 300 is not in operation. The contact element 308 istranslatable up to a predetermined distance 424 within the body 404along the longitudinal axis 416 at the second end 412. The contactelement 308 can be manufactured from brass, copper, and/or anotherconductive material.

At least one discrete retaining feature (or protuberance) in theplurality of discrete retaining features 420A, 420B can include a meansfor engaging a consumable sense feature of the plasma arc torch (e.g., aswitch 334) during operation of the plasma arc torch. The consumablesense feature can be for sensing a presence of a consumable (e.g., theretaining cap 324) secured to a torch body of the plasma arc torch, asshown in FIG. 3. In addition, at least one discrete retaining feature inthe plurality of discrete retaining features 420A, 420B (as shown, eachdiscrete retaining feature) includes a guide track 440 for interfacingwith the contact element 308. The contact element 308 includes at leastone complementary guide channel 444 for interfacing with the at leastone discrete retaining feature in the plurality of discrete retainingfeatures 420A, 420B. In some embodiments, the plurality of discreteretaining features 420A, 420B can include one or more axial stops 448A,448B (or “lip” features) that serve, e.g., as a means for locking thecontact element 308 into the cartridge. The plurality of discreteretaining features 420A, 420B is shaped to matingly engage the contactelement 308 and to define a translation path of the contact element 308within the body (e.g., corresponding to the predetermined distance 424).The translation path has two or more radial interface surfaces betweenthe contact element 308 and the body 404.

The body 404 can form a swirl ring or swirl feature of the plasma arctorch. The first end of the body 404 includes a set of passages (e.g.,passages 452A, 452B, 452C, etc.) fluidly connecting an internal surface456 of the body 404 and an external surface 460 of the body 404. Thecontact element 308 can include a snap fit feature 464 for coupling tothe body 404. The contact element 308 can be configured to slide alongthe longitudinal axis 416 during installation in the plasma arc torchupon contact with the torch plunger 332. The plurality of discreteretaining features 420A, 420B and the contact element 308 define a setof vent passages 468A, 468B. In some embodiments, the contact elementincludes a “cap” feature integrally formed with the core (e.g., as shownbelow in FIG. 6A). In some embodiments, the contact element 308 includesscalloped edges (e.g., as shown below in FIG. 6B). In some embodiments,the body 404 is formed of a thermoplastic and/or is molded.

The embodiment of the invention shown in FIGS. 3 and 4A-4B has beentested in comparison to the “fixed crown” cartridge design of FIGS. 1and 2. During testing, the cartridge thread for each setup was leftslightly untightened to generate a gap of roughly 0.040 inches. Eachsystem was run in gouging mode, which provides a lower gas pressure anda higher risk of arcing. For the “fixed crown” cartridge design of FIGS.1 and 2, two test cases out of twelve failed, and in one of those twotest cases, the torch was completely burned or destroyed. By comparison,when the same tests were run with the “floating crown” embodiment shownin FIGS. 3 and 4A-4B, the torch passed the test every time without anydamage, showing that the embodiment of FIGS. 3 and 4A-4B provides a morerobust torch and consumable design.

FIGS. 5A-5D show various views of another consumable cartridge 500 for aplasma arc torch having a contact element 540 installed therein,according to another illustrative embodiment of the invention (FIG. 5Ashows a side view; FIG. 5B shows a top view; FIG. 5C shows a sectionalview; FIG. 5D shows an exploded view). Elements of this consumablecartridge 500 can be substantially similar to those shown and describedabove in FIGS. 4A-4B. The consumable cartridge 500 includes a swirl ring508 having a body 524. The body includes a first end 512 and a secondend 516 opposite the first end 512, the first and second ends 512, 516defining a longitudinal axis 520. The body 524 is shaped to matinglyengage an electrode 528 of the plasma arc torch. The body 524 includes aset of protuberances 532A, 532B extending from the second end 516 in adirection of the longitudinal axis 520. At least one protuberance 532A,532B includes an interior guide track 536A, 536B. The swirl ring 508also includes an electrically conductive contact element 540 confined bythe set of protuberances 532A, 532B. The contact element 540 includes atleast one guide channel 544A, 544B complementary to the at least oneguide track 536A, 536B. Alignment of the contact element 540 with theswirl ring 508 is facilitated by an interaction of the at least oneguide channel 544A, 544B with the at least one guide track 536A, 536B.

At least one protuberance 532A, 532B defines a region 548 that thecontact element 540 can occupy during normal operation of the plasma arctorch. The first end 512 includes a set of passages (e.g., 552A, 552B,552C, and similar passages) fluildly connecting an internal surface 556of the swirl ring 508 and an external surface 560 of the swirl ring 508.The contact element 540 can include a snap fit feature for coupling tothe body of the swirl ring 508 (e.g., it can snap within theprotuberances and be retained within the consumable cartridge 500 by thesame). The electrode 528 includes a spring 564 configured to bias thecontact element 540 toward a cathode of the plasma arc torch. Thecontact element 540 is configured to slide along the longitudinal axis520 during installation in the plasma arc torch upon contact with aplunger of the plasma arc torch. The set of protuberances 532A, 532Bdefines a translation path (e.g., within and confined to the region 548)for the contact element 540. The set of protuberances 532A, 532B and thecontact element 540 define a set of vent passages 568A, 568B. Thetranslation path has two or more radial interface surfaces 572A, 572Bbetween the contact element 540 and the swirl ring 508. In someembodiments, one or more protuberances in the set of protuberances 532A,532B can have one or more of the following linear dimensions: a height(e.g., in a direction of the longitudinal axis) of approximately 6.3millimeters, or optionally between approximately 6.1 and 6.5millimeters, or optionally between approximately 5 and 7 millimeters; awidth (e.g., in a direction of a radius of the consumable cartridge) ofapproximately 2.0 millimeters, or optionally between approximately 1.8and 2.2 millimeters, or optionally between approximately 1 and 3millimeters; and/or a length (e.g., in a direction perpendicular to boththe width and the height) of approximately 6.9 millimeters, oroptionally between approximately 6.7 and 7.1 millimeters, or optionallybetween approximately 6 and 8 millimeters.

FIG. 6A is a perspective view of the contact element 540 for a plasmaarc torch cartridge shown in FIGS. 5A-5D, according to an illustrativeembodiment of the invention. This contact element 540 is electricallyconductive. The contact element 540 has a core 604 (e.g., a solid coreor a hollow core) and a cap 608. The cap 608 includes one or morelocating surfaces 612A, 612B for aligning with a swirl ring (e.g., swirlring 508) of a plasma arc torch cartridge and one or more channels 616for interlocking with complementary protuberances of a swirl ring. Thecontact element 540 has one or more further channels 620 for defining aset of vent passages when engaged with one or more protuberances of aswirl ring. The contact element 540 can have a similar set of featureson an opposing end (e.g., 180 degrees away from) of the contact element540 for each of the one or more channels 616 and the further channel 620(both not shown). FIG. 6B shows a similar contact element 650 with somedifferences. One notable difference is that the channels 654A, 654B forforming the vent passages have scalloped edges, rather than square orangular edges. One of ordinary skill in the art will readily appreciatethat other shapes and configurations are also possible.

FIG. 7 is a flow diagram illustrating a method 700 of operation of aplasma arc torch, according to an illustrative embodiment of theinvention. In a first step 705, a consumable cartridge is provided forthe plasma arc torch, the consumable cartridge having a cartridge framewith a first end and a second end that define a longitudinal axis, theconsumable cartridge including an electrically conductive contactelement confined by the cartridge frame. In a second step 710, theconsumable cartridge is installed in the plasma arc torch, the contactelement translated in a first direction along the longitudinal axistoward the first end once contact is made with a torch plunger of theplasma arc torch. In a third step 715, an electrode of the plasma arctorch is translated in a second direction opposite the first directionalong the longitudinal axis, the electrode contacting the contactelement during a plasma operation of the plasma arc torch. The contactelement is separated from the electrode when the plasma arc torch is notperforming the plasma operation.

FIG. 8 is a flow diagram illustrating a method 800 of assembling aplasma arc torch cartridge, according to an illustrative embodiment ofthe invention. In a first step 805, a swirl ring is provided that has abody shaped to matingly engage an electrode of a plasma arc torch, thebody including a first end and a second end that define a longitudinalaxis, and a set of protuberances extending from the second end along adirection of the longitudinal axis, the set of protuberances including aset of guide tracks. In a second step 810, an electrically conductivecontact element is provided that has a set of guide channelscomplementary to the set of guide tracks of the swirl ring. In a thirdstep 815, the contact element is installed in the swirl ring, the guidechannels of the contact element matingly engaging the set of guidetracks of the swirl ring. During installation of the contact elementinto the swirl ring the contact element translates a fixed distancealong the longitudinal axis within the swirl ring, and wherein afterinstallation the contact element is held securely within the plasma arctorch cartridge. In some embodiments, after installation the contactelement is able to translate a fixed distance within the plasma arctorch cartridge along the longitudinal axis. In some embodiments, thetranslation of the contact element in a direction of the second end islimited by at least one retaining feature disposed on an interiorsurface of at least one of the protuberances.

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in from and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the following claims.

What is claimed is:
 1. A swirl ring for a plasma arc torch, the swirlring comprising: a body configured to at least partially surround andslidingly engage an electrode of the plasma arc torch, the bodyincluding a first end and a second end opposite the first end, the firstand second ends defining a longitudinal axis, and at least oneprotuberance extending from the second end in a direction of thelongitudinal axis, wherein the at least one protuberance is configuredto engage a switch of the plasma arc torch for sensing a presence of aswirl ring in the plasma arc torch.
 2. The swirl ring of claim 1 furtherincluding a set of molded swirl holes integrally formed within the bodyof the swirl ring.
 3. The swirl ring of claim 1 further including acrimped on, unitary nozzle.
 4. The swirl ring of claim 1 furtherincluding an electrically conductive contact element confined within theat least one protuberance, wherein the at least one protuberanceincludes a set of guide tracks configured to engage a set of guidechannels on a contact element that is complementary to the set of guidetracks.
 5. The swirl ring of claim 4 wherein the at least oneprotuberance includes at least one retaining feature to confine acontact element.
 6. The swirl ring of claim 1 wherein the at least oneprotuberance includes a guide track for interfacing with a contactelement.
 7. The swirl ring of claim 1 wherein the at least oneprotuberance includes one or more axial stops.
 8. The swirl ring ofclaim 1 further including an electrode disposed within the swirl ring,the electrode including a spring configured to bias a contact elementtoward a cathode of the plasma arc torch.
 9. The swirl ring of claim 1wherein the at least one protuberance is shaped to matingly engage acontact element and to define a translation path of the contact elementwithin the swirl ring.
 10. The consumable cartridge of claim 1 whereinthe one or more protuberances has a linear height of betweenapproximately 5 and 7 millimeters.
 11. The consumable cartridge of claim1 wherein the one or more protuberances has a linear width of betweenapproximately 1 and 3 millimeters.
 12. A consumable cartridge for aplasma arc torch, the consumable cartridge including a cartridge framecomprising: means for engaging a consumable sense feature of the plasmaarc torch during operation of the plasma arc torch.
 13. The consumablecartridge of claim 10 wherein the means for engaging the consumablesense feature of the plasma arc torch during operation of the plasma arctorch includes one or more protuberances.
 14. The consumable cartridgeof claim 13 wherein the one or more protuberances includes a guide trackfor interfacing with a contact element configured to be held within theconsumable cartridge.
 15. The consumable cartridge of claim 13 whereinthe one or more protuberances includes an axial stop.
 16. The consumablecartridge of claim 13 further including an electrode disposed within theconsumable cartridge, the electrode interacting with a spring configuredto bias a contact element toward a cathode of the plasma arc torch. 17.The consumable cartridge of claim 13 wherein the one or moreprotuberances is shaped to matingly engage a contact element and todefine a translation path of the contact element within the consumablecartridge.
 18. The consumable cartridge of claim 13 wherein the one ormore protuberances has a linear height of between approximately 5 and 7millimeters.
 19. The consumable cartridge of claim 13 wherein the one ormore protuberances has a linear width of between approximately 1 and 3millimeters.
 20. A consumable cartridge for a plasma arc torch, theconsumable cartridge comprising: a body configured to at least partiallysurround and slidingly engage an electrode of the plasma arc torch, thebody including a distal first end and a proximal second end opposite thefirst end, the first and second ends defining a longitudinal axis; andan intermediate component configured to be positioned between the bodyand a safety switch of the plasma arc torch, the intermediate componentincluding at least one discrete protuberance affixed to a proximal endof the intermediate component, the discrete protuberance extending fromthe proximal end of the intermediate component in a direction of thelongitudinal axis, wherein the at least one discrete protuberance isconfigured to enable an operation of the plasma arc torch by sensing apresence of a consumable of the plasma arc torch by the safety switch.21. The consumable cartridge of claim 20 wherein the one or moreprotuberances has a linear height of between approximately 5 and 7millimeters.
 22. The consumable cartridge of claim 20 wherein the one ormore protuberances has a linear width of between approximately 1 and 3millimeters.
 23. A method of enabling an operation of a plasma arccutting torch, the method comprising: providing a protuberance on a bodyof a torch cartridge; and installing the torch cartridge in a plasma arctorch, the protuberance activating a safety switch for sensing apresence of the torch cartridge of the plasma arc torch.